1. Field
Embodiments of the invention relate to the field of bridge networking; and more specifically, to the transitioning a bridging network from a 802.1ad bridging network to a Virtual Private Local Area Network Service (VPLS) bridging network or a 802.1ah Provider Backbone Bridging (PBB) bridging network.
2. Background
A provider bridging network provides bridging access for customers to network services, such as Internet access, voice services, digital television, etc. One method of provider bridging is performed by a provider bridging network that communicates packets with customer end stations using a bridging protocol such as IEEE 802.1D, IEEE 802.1ad and/or IEEE 802.1Q Virtual Local Area Network (VLAN) tagging. A provider bridging network is composed of provider bridging edge nodes that communicate packets with customer edge bridging nodes and provider core bridging nodes that communicate packets between provider edge bridging nodes. Bridging nodes using these protocols share Media Access Control (MAC) addresses with all other bridging nodes in the provider network by broadcasting address resolution packets and unicast packets with unknown destination addresses.
However, the problem with this approach is that because these protocols share the MAC address space with all other bridging nodes, each of the bridges' MAC address table can become very large. A MAC address space is composed of one or more MAC addresses. As more end stations are added to the network, the tables for each of the bridges grow and can meet the maximum MAC address table size of these bridges. For example, a network can be composed of several to tens of thousands (or more) end stations, which can lead to very large MAC address tables.
Alternatively, a provider bridging network can communicate packets using VPLS (Request for Comment (RFC) 4761 and 4762) and/or PBB (IEEE 802.1ah). These protocols provide bridging services by establishing tunnels within the provider's bridging network. However, to use VPLS and/or PBB, the entire network needs to be upgraded at once, which can be expensive in terms of capital and operating expenditures.